To design an agricultural formulation product, the most important question to be answered is its stability. Failure to meet a set of stability requirements which usually depends on the specific market, application and regulations will certainly lead to failure of its commercialization. There are many causes of formulation instabilities, such as a) chemical instabilities due to reactions between ingredients (actives and/or inerts, etc.), photo-degradations, and oxidations, etc., b) physical instabilities due to phase separations (Ostwald ripening, crystallization, sedimentation or creaming etc.) and c) environmental factors (temperature, humidity/moisture, etc.). In today's agrichemical market, it becomes increasingly common to design formulations to contain multiple active ingredients and their required solvents, safeners, and/or adjuvants, etc., in order to achieve the optimal spectrum, efficacy, and delivery efficiency, which consequently makes formulation stability more and more challenging. Therefore, technologies that can effectively isolate, hinder, or eliminate, adverse reactions or interactions between incompatible ingredients are often critical for a successful product.
The emulsifiable concentrate (EC) is one of the most common formulation types for many agricultural products, where mixtures of oil soluble active ingredients and emulsifying agents (surfactants) are dissolved in an organic solvent. The emulsifying agent enables the EC to disperse easily in water, thereby forming a “milky” and homogenous emulsion. Emulsifiable concentrates are generally easy to mix and do not settle out quickly when agitation is stopped, are relatively easy to handle, transport and store, are not abrasive to spray equipment and do not clog spray screens and nozzles and are easy to manufacture. However, many challenges may exist, particularly when a carboxylic acid herbicide is mixed with an ester of a different carboxylic acid herbicide. For example, a composition containing fluoroxypyr meptyl ester and clopyralid free acid has been found to be extremely useful because of the complimentary spectrum of weed control of the individual components. However, in typical emulsifiable concentrate formulations, transesterification to clopyralid meptyl ester and fluoroxypyr free acid can occur. This is problematic from a regulatory perspective because both the free acid and particular ester of both the active herbicidal ingredients may not be registered. Thus it would be desirable to retard such transesterification within the formulation.
In addition, when a triazolopyrimidine herbicide having at least one methoxy group on the triazolopyrimidine ring like florasulam, N-(2,6-difluorophenyl)-8-fluoro-5-methoxy[1,2,4]triazolo[1,5-c]pyrimidine-2-sulfonamide, is incorporated into an emulsifiable concentrate, particularly in admixture with a carboxylic acid herbicide and/or an ester of a carboxylic acid herbicide, it often is degraded to the herbicidally inactive hydroxy analog. Similarly, it would be desirable to prevent such degradation within the formulation.